Coaxial cables with shaped metallic conductors

ABSTRACT

The present invention provides a coaxial cable which comprises a cable core encased in a polymeric layer, enclosing the cable core with a pair of shaped conductors; extruding a layer of polymer over the shaped conductors; and cabling armor wire layer about the layer of polymer to form the coaxial cable.

BACKGROUND

The disclosure is related in general to wellsite equipment such as oilfield surface equipment, oilfield cables and the like.

Currently, coaxial cable manufacture is a tedious, time-intensive, expensive process requiring a great deal of complex machinery. A drawback to the process is in cabling the thin-wire-braiding shielded conductor onto the cable core. As shown in FIG. 1, a typical traditional coaxial cable manufacturing process may comprise a series of thirty spools of thin wire rotating in alternating directions around a central insulated conductor. The machinery required may be complex and may require a large footprint in a manufacturing facility. The process may also tedious to set up and must run slowly to minimize breakage of the thin wires used. Manufacturing a 24,000-foot cable may take 48 hours for the wire braiding process alone. The cable must then be transferred to a separate line where the outer insulation is extruded over the braiding. This process may require an additional six hours. Terminating the braided wire conductor to downhole tools may also be a complex process.

It remains desirable to provide improvements in wireline cables and/or downhole assemblies.

SUMMARY AND DETAILED DESCRIPTION

Referring now to FIG. 2, in an embodiment 1, the coaxial cable core may be formed using a polymer-insulated, stranded conductor placed between two semi-circular-profile shaped metallic wires or conductors. The cable core is held in place by extruding a polymeric jacket over the shaped wires as they come together over the central stranded conductors. Bare or jacketed armor wire strength members (which may be solid strength members or stranded strength members) are placed over the cable core to complete the cable. In operation, an electrical signal is passed down the central conductor with a return path on the shaped wires.

Referring again to FIG. 2, in an embodiment 2, optical fibers are placed inside the semi-circular-profile shaped metallic wires or conductors with a polymeric jacket over the shaped wires. Bare or jacketed armor wires strength members (which may be solid strength members or stranded strength members) are placed over the cable core to complete the cable. In operation, telemetry is provided on the optical fibers and an electrical signal is passed down the shaped wires with a return path on the armor wire strength members.

Referring again to FIG. 2, in an embodiment 3 a second layer of insulated shaped wires or conductors is added to the configuration of Embodiment 2, which provides an insulated electrical return path.

In contrast to the process shown in FIG. 1, the embodiments described in this document may take a bare central stranded conductor, apply insulation over that conductor, apply two preferably semi-circular shaped wires or conductors over the insulation (which take the place of the braided wires), and then apply the outer layer of insulation in a single pass, as shown in FIG. 3. This entire process may take approximately six hours for a 24,000-foot cable core (as opposed to fifty-four hours for a typical conventional process), is far less complicated, and takes up a much smaller footprint on the shop floor. As compared to the braided wires, the semi-circular wires may also be much easier to terminate to downhole tools.

In an embodiment 1 shown in FIG. 4, a coaxial cable with polymer-insulated stranded conductor inside half-shell-profile shaped metallic wires or conductors is disclosed. A polymer jacket is placed over the half-shell wires followed by two counter-helically applied layers of armor wire strength members. Referring now to FIG. 4.1, a polymer-insulated stranded metallic conductor is placed at the center of the cable. In FIG. 4.2, two semi-circular-profile shaped wires are added with inner profiles combining to match the outer diameter of the polymer-insulated conductor. In FIG. 4.3, a layer of polymer is extruded over the shaped wires to hold them together as the shaped wires come together over the central conductor. In FIG. 4.4, an inner layer of armor wire strength members is cabled helically over and slightly embedded into the polymeric layer over the shaped wires. In FIG. 4.5, an outer layer of armor wire strength members is cabled over and counter-helically to the inner armor wire layer.

In an embodiment 2 shown in FIG. 5, a coaxial cable with optical fibers inside half-shell-profile shaped metallic wires is disclosed comprising a number of optical fibers in a soft polymer filler material encased between a pair of half-shell-profile shaped metallic wires. A second polymer jacket is placed over the half-shell wires followed by two counter-helically applied layers of armor wire strength members. Referring now to FIG. 5.1, a number of optical fibers encased in a soft polymer are placed at the center of the cable. The optical fibers and filler may be brought together in the same manufacturing line (or location) as step 2 (shown in FIG. 5.2) and step 3 (shown in FIG. 5.3), or may be cabled together in a soft polymer jacket in a separate process. In FIG. 5.2, two semi-circular-profile shaped wires are added with inner profiles combining to match the outer diameter of the polymer-jacketed optical fiber(s). If the optical fibers and soft polymer filler have been brought together immediately prior to applying the shaped wires, sufficient soft polymer will be used to completely fill all interstitial spaces between the optical fibers and the shaped wires. In FIG. 5.3, as the shaped wires come together over the optical fibers, a layer of polymer is extruded over the shaped wires to hold them together. The steps shown in FIGS. 5.1, 5.2, and 5.3 may be performed concurrently. In FIG. 5.4, an inner layer of armor wire strength members is cabled helically over and slightly embedded into the polymeric layer over the shaped wires. In FIG. 5.5, an outer layer of armor wire strength members is cabled over and counter-helically to the inner armor wire layer.

In an embodiment 3 shown in FIG. 6, a coaxial cable with optical fibers inside two insulation-separated layers of half-shell-profile shaped metallic wires comprising a number of optical fibers in a soft polymer filler material encased between two layers of paired half-shell-profile shaped metallic wires is disclosed. Additional polymer jackets are placed between the two layers of half-shell wires and over the outer half-shell-wire layer. The half-shell-wire layers may be offset from one another by 90 degrees in order to prevent preferential bending in the completed cable. Two counter-helically applied layers of armor wire strength members complete the cable.

Referring now to FIG. 6.1, a number of optical fibers encased in a soft polymer are placed at the center of the cable. The optical fibers and filler may be brought together in the same manufacturing line (or location) as Steps 2 and 3, or may be cabled together in a soft polymer jacket in a separate process. In FIG. 6.2, two semi-circular-profile shaped wires are added with inner profiles combining to match the outer diameter of the polymer-jacketed optical fiber(s). If the optical fibers and soft polymer filler have been brought together immediately prior to applying the shaped wires, sufficient soft polymer will be used to completely fill all interstitial spaces between the optical fibers and the shaped wires. In FIG. 6.3, as the shaped wires come together over the optical fibers, a layer of polymer is extruded over the shaped wires to hold them together. In FIG. 6.4, two more semi-circular-profile shaped wires are added with inner profiles combining to match the outer diameter of the polymer-jacketed optical fiber(s). This second pair of shaped wires may be offset from the first pair of shaped by about 90 degrees to prevent preferential bending in the completed cable. If the optical fibers and soft polymer filler have been brought together immediately prior to applying the shaped wires, sufficient soft polymer will be used to completely fill all interstitial spaces between the optical fibers and the shaped wires. In FIG. 6.5, as the shaped wires come together over the optical fibers, a layer of polymer is extruded over the shaped wires to hold them together. The steps shown in FIGS. 6.1, 6.2, 6.3, 6.4, and/or 6.5 may be performed concurrently. In FIG. 6.6, an inner layer of armor wire strength members is cabled helically over and slightly embedded into the polymeric layer over the outer layer of shaped wires. In FIG. 6.7, an outer layer of armor wire strength members is cabled over and counter-helically to the inner armor wire layer. The strength members may be solid members (as shown), or stranded armor wire members.

Referring now to FIG. 7, polymeric-jacketing options for armor wire strength member layers are disclosed. Depending on application requirements, the armor wire strength members of embodiments 1, 2, and/or 3 may be partially or completely jacketed with pure polymer or polymer amended with short fibers. FIG. 5 shows jacketing options applied to embodiments 1, 2, and 3, respectively. For a cable with internal jacketing, the process would stop after the steps shown in FIGS. 7.3. For a completely jacketed cable, the process would continue with the steps shown in FIG. 7.4. The basic armor wire cabling and jacketing process is as follows. In FIGS. 7.1, an inner layer of armor wire strength members is cabled helically over the polymer jacket. Preferably immediately prior to cabling, the cable passes through an infrared heat source to allow the armor wires to be partially embedded into the softened polymer. In FIGS. 7.2, a layer of polymer is extruded over the inner armor wire layer. This layer of polymer may be pure polymer or may be polymer amended with short fibers. In FIGS. 7.3, an outer layer of armor wire strength members is cabled over and counter-helically to the inner armor wire layer. Immediately prior to cabling, the cable passes through an infrared heat source to allow the armor wires to be partially embedded into the softened polymer. In FIGS. 7.4, a final layer of polymer is extruded over the inner armor wire layer. This final layer of polymer may be pure polymer or may be amended with short fibers.

The preceding description has been presented with reference to present embodiments. Persons skilled in the art and technology to which this disclosure pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, and scope of this invention. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope. 

We claim:
 1. A cable as shown and described.
 2. A method for using a cable as shown and described.
 3. A method for manufacturing a coaxial cable, comprising: providing a cable core encased in a polymeric layer; enclosing the cable core with a pair of shaped conductors; extruding a layer of polymer over the shaped conductors; and cabling an armor wire layer about the layer of polymer to form the coaxial cable.
 4. The method of claim 3 wherein providing a cable core comprises providing a polymer-insulated stranded metallic conductor.
 5. The method of claim 3 wherein providing a cable core comprises providing a number of optical fibers encased in a soft polymer.
 6. The method of claim 3 further comprising cabling a second armor wire layer about the armor wire layer to form the coaxial cable.
 7. The method of claim 6 further comprising extruding a layer of polymer over the armor wire layer prior to cabling the second armor wire layer.
 8. The method of claim 7 further comprising heating the polymeric layer prior to cabling the second armor wire layer.
 9. The method of claim 8 further extruding a layer of polymer over the second armor wire layer.
 10. The method of claim 9 further comprising heating the polymeric layer prior to cabling the second armor wire layer.
 11. The method of claim 3 further comprising enclosing layer of polymer and the cable core with a second pair of shaped conductors and extruding a second layer of polymer over the second pair of shaped conductors.
 12. The method of claim 11 wherein the second pair of shaped conductors is offset from the shaped conductors by a predetermined amount.
 13. The method of claim 3 wherein the cable comprises a wireline cable.
 14. The method of claim 3 wherein the cable comprises a seismic cable.
 15. The method of claim 3 wherein the cable comprises a slickline cable. 